Noise isolation sheet

ABSTRACT

There is provided a noise isolation sheet  10  which is comprised of an optional number of closed-cell foamed layer  11,  open-cell foamed layer  12  and fibered noise absorbing material  13,  being laminated in an optional order, and which insulates the noise near  1000  Hz. Further, there is provided a noise isolation sheet  10  comprised of an optional number of the closed-cell foamed layer  11  and the fibered noise absorbing material  13  being laminated in an optional order. There is also provided a noise isolation sheet  10  comprised of an optional number of the open-cell foamed layer  12  and the fibered noise absorbing material  13  being laminated in an optional order. Each noise isolation sheet  10  is used to partially or fully cover an interior side of a door inner panel of a vehicle.

BACKGROUND OF THE INVENTION

This invention relates to a noise isolation sheet which is used, for example, as a sheet installed to an interior side of an automobile door.

There have conventionally been applied various noise isolation means to an inner side of an automobile door with an aim of preventing external noise from invading into an interior of the automobile as well as preventing internal noise from leaking to an outside. For example, there have been invented such means that a felt or urethane is attached to a backside of an interior door trim which is installed to an interior side of a door inner panel, and that an urethane made product is attached to a door inner panel.

Regarding to the prior art described above, the applicant of this invention has invented a noise isolation sheet and filed it (Japanese Patent Publication No. 2004-020415) in order to improve a noise isolation property of the conventional noise isolation means. As illustrated in FIG. 15, the noise isolation sheet comprises a foam body (a closed-cell foamed layer 11) which is provided with an infinite number of closed cells 11 a interspersed therein, and another foam body (an open-cell foamed layer 12) which is provided with open cells 12 a interspersed therein.

Further, there has been invented a sound-absorbing material for absorbing noise generated by the aspiration of the air in a combustion engine (see, for example Japanese Unexamined Patent Publication No. 8-146967 and Japanese Patent Publication No. 2503215.)

However, although the noise isolation sheet filed by the applicant of this invention is superior in a noise isolation property compared to the conventional art comprising the felt or the urethane, and it, as illustrated in FIG. 16, is also superior in the noise isolation property as well as a noise absorbing property against the noise having a frequency of around 3000 Hz or higher, it should further be improved in the noise isolation property as well as the noise absorbing property against the noise near 1000 Hz. In FIG. 16, “(1) NI sheet” is the noise isolation sheet the applicant of this invention has previously filed. Further, “(2) Thinsulate” is a name of a product manufactured by SUMITOMO 3M Ltd., “(3) chip felt” is an urethane chip felt, and “(4) pet felt” is a resin felt, and all of them are fibriform noise absorbing materials having a gravity of about 0.02. Further, “(5) flexible urethane” is spongiose, and is a flexible foam body formed by expanding materials which is mainly comprised of polyol and polyisocyanate. It has a gravity of about 0.02. It should be noted that “t” in each corresponding parenthesis indicates a thickness (mm).

Further, the noise absorbing material disclosed in the Unexamined Patent Publication No. 8-146967 is only effective in absorbing the noise in a range of 100 Hz to 300 Hz, and it is not satisfying in absorbing the noise near 1000 Hz. The noise absorbing material disclosed in the Japanese Patent Publication No. 2503215 is not satisfying either in absorbing the noise near 1000 Hz.

It is therefore an object of this invention to provide a noise isolation sheet which is also fully effective in isolating the noise near 1000 Hz.

SUMMARY OF THE INVENTION

In order to solve the above mentioned problems, a noise isolation sheet according to a first aspect of the invention is characterized in that it comprises an optional number of closed-cell foamed layer (11), open-cell foamed layer (12) and fibered noise absorbing material (13), wherein the closed-cell foamed layer (11), open-cell foamed layer (12) and fibered noise absorbing material (13) are laminated in an optional order.

The closed-cell foamed layer (11) is a foam body in which an infinite number of dosed cells (11 a) are dispersedly formed therein (see FIG. 15). The open-cell layer (12) is a foam body in which open cells (12 a) are dispersedly formed therein, wherein each open cell (12 a) is formed such that adjacent dosed cells (11 a) come to communicate with each other (see FIG. 15). The open-cell foamed layer (12) includes a semi-open-cell foamed layer (not illustrated) which comprises both the dosed cells (11 a) and open cells (12 a) dispersedly formed therein.

A noise isolation sheet (10) according to a second aspect of the invention is characterized in that it comprises an optional number of closed-cell foamed layer (11) and fibered noise absorbing material (13), wherein the closed-cell foamed layer (11) and fibered noise absorbing material (13) are laminated in an optional order.

A noise isolation sheet (10) according to a third aspect of the invention is characterized in that it comprises an optional number of open-cell foamed layer (12) and fibered noise absorbing material (13), wherein the open-cell foamed layer (12) and fibered noise absorbing material (13) are laminated in an optional order.

A noise isolation sheet (10) according to a fourth aspect of the invention is characterized in that it is used for partially or fully covering an interior side of a door inner panel (1) of a vehicle, comprising an optional number of closed-cell foamed layer (11), open-cell foamed layer (12) and fibered noise absorbing material (13), wherein the closed-cell foamed layer (11), open-cell foamed layer (12) and fibered noise absorbing material (13) are laminated in an optional order.

A noise isolation sheet (10) according to a fifth aspect of the invention is characterized in that it is used for partially or fully covering an interior side of a door inner panel (1) of a vehicle, comprising an optional number of closed-cell foamed layer (11) and fibered noise absorbing material (13), wherein the closed-cell foamed layer (11) and fibered noise absorbing material (13) are laminated in an optional order.

A noise isolation sheet according to a sixth aspect of the invention is characterized in that it is used for partially or fully covering an interior side of a door inner panel (1) of a vehicle, comprising an optional number of open-cell foamed layer (12) and fibered noise absorbing material (13), wherein the open-cell foamed layer (12) and fibered noise absorbing material (13) are laminated in an optional order.

A noise isolation sheet (10) according to a seventh aspect of the invention is characterized in that, in the fourth or fifth aspect of the invention, a layer positioned in an outermost exterior side of a vehicle is the closed-cell foamed layer (11).

A noise isolation sheet (10) according to a eighth aspect of the invention is characterized in that, in the sixth invention, a layer positioned in an outermost exterior side of a vehicle is the open-cell foamed layer (12).

A noise isolation sheet according to a ninth aspect of the invention is characterized in that, in any of the preceding claims, the fibered noise absorbing material (13) is an urethane chip felt or resin felt.

The numeral in each parenthesis indicates a corresponding element or matter disclosed in the drawings and the after-mentioned preferred embodiment of the invention. The same numerals are provided to the similar portions disclosed in the prior art.

According to the noise isolation sheet in the first aspect of the invention, the fibered noise absorbing material is laminated in addition to the closed-cell foamed layer and the open-cell foamed layer, so that as illustrated in FIG. 14, there can also be obtained a great noise isolation property against the noise near 1000 Hz by a performance of the fibered noise absorbing material.

The graph shown in FIG. 14 discloses numerical values of the sound transmission loss (TL [db]) obtained by an experimental test completed by using four different types of noise isolation sheets. According to this test result, it is understood that the noise isolation sheet according to the invention comprised of the closed-cell foamed layer, the open-cell foamed layer and the fibered noise absorbing material (which is indicated in the graph as “(3) NI sheet+Thinsulate”) is most effective in the noise isolation property against the noise near 1000 Hz.

In addition, another noise isolation sheet according to the invention (which is indicated as “(4) NI sheet+Thinsulate+NI sheet”) which is comprised of two pieces of NI sheets and the fibered noise absorbing material, wherein each NI sheet is composed of the closed-cell foamed layer and the open-cell foamed layer, comes next to the above-mentioned sheet. Further, the conventional sheet comprised of the closed-cell foamed layer and the open-cell foamed layer (“(1) NI sheet”) comes next, followed by the sheet comprised merely of the fibered noise absorbing material (“(2) Thinsulate (1 piece)”). It should be noted that the noise isolation sheet “(4)” according to the invention which is comprised of two NI sheets and the fibered noise absorbing material is most effective in the noise isolation property against the noise in a range at 1000 Hz and higher.

Further, the closed-cell foamed layer is also highly effective in the waterproof property, while the open-cell foamed layer is highly effective in the noise isolation property.

According to the noise isolation sheet in the second aspect of the invention, it is comprised of the closed-cell foamed layer and the fibered noise absorbing material which is laminated on the closed-cell foamed layer, so that it is highly effective in isolating the noise near 1000 Hz by a performance of the fibered noise absorbing material. Further, this noise isolation sheet is also highly effective in the waterproof property by a performance of the closed-cell foamed layer.

According to the noise isolation sheet in the third aspect of the invention, the fibered noise absorbing material is laminated on the open-cell foamed layer, so that it is also highly effective in isolating the noise near 1000 Hz. Further, this noise isolation sheet demonstrates a higher property in isolating the noise by a performance of the open-cell foamed layer.

According to the noise isolation sheet in the fourth aspect of the invention, the fibered noise absorbing material is laminated in addition to the closed-cell foamed layer and the open-cell foamed layer, so that it is highly effective in isolating the noise near 1000 Hz. Therefore, by covering with this noise isolation sheet an interior side of a door inner panel of a vehicle, an external noise is effectively prevented from invading into an interior of the vehicle, while an internal noise is prevented from leaking to the external of the vehicle.

According to the noise isolation sheet in the fifth aspect of the invention, the closed-cell foamed layer and the fibered noise absorbing material are laminated, so that it is highly effective in isolating the noise near 1000 Hz, and is improved in the noise isolating property of an interior of a vehicle. Further, a door of a vehicle is improved in the waterproof property by a performance of the closed-cell foamed layer.

According to the noise isolation sheet in the sixth aspect of the invention, the open-cell foamed layer and the fibered noise absorbing material are laminated, so that it is also highly effective in isolating the noise near 1000 Hz, and it can improve the noise isolation property of an interior of a vehicle. Further, it can demonstrate the higher noise isolation property by a great performance of the open-cell foamed layer in isolating the noise.

According to the noise isolation sheet in the seventh aspect of the invention, the layer positioned in the outermost exterior side of the vehicle in the fourth or fifth aspect of the invention is the closed-cell foamed layer, so that the door of the vehicle can be improved in the waterproof property by a performance of the closed-cell foamed layer which is highly effective in the waterproof property.

According to the noise isolation sheet in the eighth aspect of the invention, the layer positioned in the outermost external side of the vehicle in the sixth aspect of the invention is the open-cell foamed layer, so that the vehicle door is improved in the noise isolation property by a performance of the open-cell foamed layer which is greatly effective in isolating the noise.

According to the noise isolation sheet in the ninth aspect of the invention, the fibered noise absorbing material in any of the preceding invention is the urethane chip felt or the resin felt, so that it can demonstrate a highly effective noise isolation property, and that it is economical.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing a noise isolation sheet 10 according to a preferred embodiment of the invention, which is being installed to an automobile door;

FIG. 2 is a sectional view along line I-I in FIG. 1 showing a noise isolation sheet according to a first preferred embodiment of the invention;

FIG. 3 is a sectional view along line I-I in FIG. 1 showing another aspect of a noise isolation sheet according to the first preferred embodiment of the invention;

FIG. 4 is a sectional view along line I-I in FIG. 1 showing further another aspect of a noise isolation sheet according to the first preferred embodiment of the invention.

FIG. 5 is a sectional view along line I-I in FIG. 1 showing still another aspect of a noise isolation sheet according to the first preferred embodiment of the invention;

FIG. 6 is a sectional view along line I-I in FIG. 1 showing still further aspect of a noise isolation sheet according to the first preferred embodiment of the invention;

FIG. 7 is a sectional view along line I-I in FIG. 1 showing a noise isolation sheet according to a second preferred embodiment of the invention;

FIG. 8 is a sectional view along line I-I in FIG. 1 showing another noise isolation sheet according to a second preferred embodiment of the invention;

FIG. 9 is a sectional view along line I-I in FIG. 1 showing a noise isolation sheet according to a third preferred embodiment of the invention;

FIG. 10 is a sectional view along line I-I in FIG. 1 showing another noise isolation sheet according to a third preferred embodiment of the invention;

FIG. 11 is a table showing an experimental test result of the transmitted sound of the noise isolation sheet according to the preferred embodiment of the invention;

FIG. 12 is a table showing an experimental test result of the sound transmission loss of the noise isolation sheet according to the preferred embodiment of the invention;

FIG. 13 is a graph showing an experimental test result of the sound transmission loss of the noise isolation sheet according to the preferred embodiment of the invention;

FIG. 14 is another graph showing an experimental test result of the sound transmission loss of the noise isolation sheet according to the preferred embodiment of the invention;

FIG. 15 is a sectional view showing a sheet the applicant of this invention has previously filed;

and FIG. 16 is a graph showing the sound absorption coefficient of the sheet the applicant of this invention has previously filed as well as the sheets formed by other materials.

DESCRIPTION OF PREFERRED EMBODIMENT

A noise isolation sheet 10 according to a first preferred embodiment of the invention will be described referring to FIGS. 1 to 6. FIG. 1 is an exploded perspective view showing the noise isolation sheet 10 in an installation posture. Each of FIGS. 2 to 6 is a sectional view along line I-I in FIG. 1 showing the noise isolation sheet 10.

Each of those noise isolation sheets 10 is installed between a door inner panel 1 of an automobile and an interior door trim 2 fully (or partially) covering an interior side of the door inner panel 1. The noise isolation sheet 10 is comprised of a closed-cell foamed layer 11, an open-cell foamed layer 12 and a fibered noise absorbing material 13.

The closed-cell foamed layer 11 and the open-cell foamed layer 12 can be made of a synthetic rubber such as EPDM, CR, SBR and NBR, and in this preferred embodiment, they are made of EPDM for a reason that it is easily controlled in its gravity. The fibered noise absorbing material 13 is formed by Thinsulate (a product name), an urethane chip felt or a resin felt. Those materials do not make much difference in the noise isolation property.

In all of the noise isolation sheets 10, the closed-cell foamed layer 11 is positioned in an outermost external side of an automobile door in order to improve the waterproof property of the door by preventing the rain water and the like from invading into an interior of the vehicle at an exterior side of the vehicle by a performance of the closed-cell foamed layer 11 which is highly effective in the waterproof property. Further, by positioning the open-cell foamed layer 12 and the fibered noise absorbing material 13 in an internal side of the vehicle, the noise isolation property of the noise isolation sheet 10 against the noise near 1000 Hz is improved by a performance of the layer 12 and the material 13, both of which are highly effective in the noise isolation property.

As illustrated in FIGS. 2 and 3, the noise isolation sheet 10 according to the preferred embodiment of the invention may be comprised of a single layer of the closed-cell foamed layer 11, the open-cell foamed layer 12 and the fibered noise absorbing material 13, or as illustrated in FIGS. 4 to 6, it may be comprised of two layers (or more than two layers) of the closed-cell foamed layers 11 and the open-cell foamed layers 12 (or the fibered noise absorbing materials 13). Further, the positioning of the layers 11, 12 and the material 13 can be optionally arranged depending on a demand.

Referring to FIGS. 1, 7 and 8, a noise isolation sheet according to a second preferred embodiment of the invention will be described. Each of FIGS. 7 and 8 is a sectional view along line I-I in FIG. 1 showing the noise isolation sheet 10.

Each of the noise isolation sheets 10 is also installed to an interior side of a door inner panel 1 of an automobile, and it is comprised of a closed-cell foamed layer(s) 11 and a fibered noise absorbing materials 13. The noise isolation sheet 10 shown in FIG. 7 is comprised of a single layer of the closed-cell foamed layer 11 and the fibered noise absorbing material 13, whereas the noise isolation sheet 10 shown in FIG. 8 is comprised of two layers of the closed-cell foamed layers 11, thereby improving the waterproof property as well as the noise isolation property. More than two layers of the fibered noise absorbing materials 13 can be provided.

There will be described a noise isolation sheet 10 according to a third preferred embodiment of the invention referring to FIGS. 1, 9 and 10. Each of FIGS. 9 and 10 is a sectional view along line I-I in FIG. 1 showing the noise isolation sheet 10.

This noise isolation 10 is also installed to an interior side of a door inner panel of an automobile, and is comprised of a open-cell foamed layer(s) 12 and a fibered noise absorbing materials 13. Both the open-cell foamed layer 12 and the fibered noise absorbing material 13 are highly effective in the noise isolation property, so that this sheet 10 is greatly effective in isolating the noise of any frequency including the noise near 1000 Hz. A number and a position of the open-cell foamed layer 12 as well as the fibered noise absorbing material 13 are not limited.

The inventor of this invention and his colleagues have completed an experimental test to seek the noise isolation effect of the noise isolation sheet 10 according to the preferred embodiment and compared it with other sheets.

The table shown in FIG. 11 indicates the transmitted sound of the noise isolation sheet 10 according to the preferred embodiment of the invention with the transmitted sound of other sheets. In this table, “NI sheet” is, as previously indicated, a sheet in which a dosed-cell foamed layer 11 and an open-cell foamed layer 12 are laminated. As shown in this table, the numeric values of the transmitted sound near 1000 Hz is relatively low according to the noise isolation sheet 10 of the preferred embodiment of the invention (which are indicated as “NI sheet+Thinsulate”, “NI sheet+felt”, “NI sheet+Thinsulate+NI sheet”, and “NI sheet+felt+NI sheet”). It is understood from this result that the noise isolation sheet 10 according to the preferred embodiment of the invention is highly effective compared to the conventional sheets.

The table shown in FIG. 12 indicates the sound transmission loss of the noise isolation sheet 10 according to the preferred embodiment of the invention with the sound transmission loss of other sheets. FIG. 13 is a graph prepared based on the numeric values shown in FIG. 12. The graph shown in FIG. 14, which is previously described, is also prepared based on the numeric values shown in FIG. 12 (it should be noted that the numeric values of “NI sheet (1 piece)” and “Thinsulate (1 piece)” are excluded from the table in FIG. 12.)

It is understood from the table and the graph that the noise isolation sheet 10 (“(3) NI sheet+Thinsulate”) according to the preferred embodiment of the invention is the highest in the sound transmission loss in a range of slightly lower than 1000 Hz, and is highly effective in the noise isolation property compared to the conventional sheets. It should be noted that the other noise isolation sheets according to other preferred embodiments of the invention (“(5) NI sheet+Thinsulate+NI sheet” and “(6) NI sheet+felt+NI sheet”) are also highly effective in the noise isolation property in a range at 1000 Hz and higher as well as a range at slightly lower than 1000 Hz.

Although, in the above-mentioned preferred embodiments, the noise isolation sheet is described in a case that it is installed to an automobile door, this invention is not limited to such use, and it can be applied to other vehicles such as a train and an airplane as well as a building and the like. 

1. A noise isolation sheet characterized in that it comprises an optional number of closed-cell foamed layer, open-cell foamed layer and fibered noise absorbing material, wherein said closed-cell foamed layer, open-cell foamed layer and fibered noise absorbing material are laminated in an optional order.
 2. A noise isolation sheet characterized in that it comprises an optional number of closed-cell foamed layer and fibered noise absorbing material, wherein said closed-cell foamed layer and fibered noise absorbing material are laminated in an optional order.
 3. A noise isolation sheet characterized in that it comprises an optional number of open-cell foamed layer and fibered noise absorbing material, wherein said open-cell foamed layer and fibered noise absorbing material are laminated in an optional order.
 4. A noise isolation sheet characterized in that it is used for partially or fully covering an interior side of a door inner panel of a vehicle, comprising an optional number of closed-cell foamed layer, open-cell foamed layer and fibered noise absorbing material, wherein said closed-cell foamed layer, open-cell foamed layer and fibered noise absorbing material are laminated in an optional order.
 5. A noise isolation sheet characterized in that it is used for partially or fully covering an interior side of a door inner panel of a vehicle, comprising an optional number of closed-cell foamed layer and fibered noise absorbing material, wherein said closed-cell foamed layer and fibered noise absorbing material are laminated in an optional order.
 6. A noise isolation sheet characterized in that it is used for partially or fully covering an interior side of a door inner panel of a vehicle, comprising an optional number of open-cell foamed layer and fibered noise absorbing material, wherein said open-cell foamed layer and fibered noise absorbing material are laminated in an optional order.
 7. A noise isolation sheet claimed in claim 4 characterized in that a layer positioned in an outermost exterior side of a vehicle is the closed-cell foamed layer.
 8. A noise isolation sheet claimed in claim 6 characterized in that a layer positioned in an outermost exterior side of a vehicle is the open-cell foamed layer.
 9. A noise isolation sheet claimed in claim 1 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 10. A noise isolation sheet claimed in claim 5 characterized in that a layer positioned in an outermost exterior side of a vehicle is the closed-cell foamed layer.
 11. A noise isolation sheet claimed in claim 10 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 12. A noise isolation sheet claimed in claim 1 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 13. A noise isolation sheet claimed in claim 2 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 14. A noise isolation sheet claimed in claim 3 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 15. A noise isolation sheet claimed in claim 4 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 16. A noise isolation sheet claimed in claim 5 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 17. A noise isolation sheet claimed in claim 6 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 18. A noise isolation sheet claimed in claim 7 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt.
 19. A noise isolation sheet claimed in claim 8 characterized in that said fibered noise absorbing material is an urethane chip felt or resin felt. 